Abstract : Conical acrylic windows for fixed ocean-floor structures were placed under short-term loading (pressurization from zero to failure at a fixed rate). The windows, of different thicknesses and different included conical angles, were subjected to various applied pressures, and their subsequent behavior was studied. Acrylic windows, in the form of truncated cones with included angles of 30?, 60?, 90?, 120?, and 150?, were tested to destruction at ambient room temperature by applying hydrostatic pressure to the base of the truncated cone at a continuous rate of 650 psi/min. The pressure at which the windows failed and the magnitude of displacement through the window mounting at different pressure levels were recorded. The ultimate strength of the conical windows (denoted by the critical pressure at which actual failure occurred) was found to be related both to thickness and included conical angle. Graphs are presented defining the relationships of critical pressure versus thickness-to-diameter ratio, and pressure versus magnitude of displacement for the windows. Nondimensional scaling factors for critical pressure and displacement applicable to large-diameter windows are discussed and presented in graphic form. (Author)